This invention relates to a copying apparatus with convertible copying magnification, more specifically to an electronic copying apparatus with a scanning optical unit.
In an electronic copying apparatus, it is desirable to secure copying with convertible magnification, i.e., with reduced or enlarged original surface as well as copying with full-scale original surface (hereinafter referred to as full-scale copying or 1 : 1 copying), while a variety of systems for conversion of magnification have conventionally been developed and put to practical use. For example, some systems have various lenses for convertion with each magnification, while others may secure exposure by changing the location of lenses and moving incident-side mirrors at different speeds, though all these systems have complicated configurations and may produce blurred pictures due to vibration of moving parts. A typical example of these systems is as illustrated in U.S. Pat. No. 3,837,743. This is so designed that spare mirrors, previously contained in the optical unit, are used to change the optical distance in conversion of magnification and the original or supporting table is moved with a movement of the optical unit in prescribed relation therewith. The copying apparatus of this U.S. patent is disadvantageous in that the driving system is complicated and large-sized because the relatively heavy supporting table requires to be moved at a speed according to the copying magnification, that it is difficult to synchronize the respective moving members to each other and that such movement of the supporting table is accompanied by vibration of the whole apparatus to cause blurred pictures, thereby preventing production of distinct copies.